The present invention relates to an operation tool (surgical instrument) that preferably has at least one working section.
During operations and examinations, location and/or function of the surgical instrument is determined more and morexe2x80x94especially in view of using possible low invasive, i.e. minimally invasive interventionxe2x80x94based on magnetic resonance, whereby, for example, a so-called magnetic resonance tomograph (image) is used. Magnetic resonancexe2x80x94here abbreviated as MRxe2x80x94is, thus, used here for the illustration of spatial relationships in a body, for example the location of tissues, organs and/or surgical instruments, wherein a relatively strong magnetic field is applied and substances and materials can be differentiated due to the different magnetic characteristics. Operations and examinations in which MR is used supportively, e.g. as a control function or as a guide, for example to the correct location of an instrument, will be abbreviated here as well to xe2x80x9cMR-guided and/or MR-basedxe2x80x9d.
In order to be able to use MR, the use of MR-compatible substances for surgical instruments or their working sections is necessary. When using conventional materials, such as stainless steel, such artifacts (defect image) result that MR makes no or only an insufficient (figurative or spatial) resolution possible.
DE 198 11 033 C1 discloses a surgical instrument and method for its production. In order to reduce the weight of the surgical instrument, it is provided that it consists entirely or in essential parts of aluminum or an aluminum alloy and that the surface of the aluminum or the aluminum alloy is provided with a thin aluminum-nitride layer of, in particular, 1 to 10 xcexcm. It has been seen, for example, that such instruments produce practically no artificial signals (artifacts) in magnetic resonance tomography (imaging). The aluminum-nitride layer is preferably achieved by surface-melting the parts consisting of aluminum or an aluminum alloy by means of laser radiation in a nitrogen atmosphere. This is very elaborate. The aluminum-nitride layer is relatively thick, so that the risk of an undesired peeling or splitting exists, in particular in the case of intense strain on the surgical instrument.
DE 198 11 033 C1 provides only an aluminum-nitride layer and, because of this, accomplishes that contact of the metallic aluminum to the surroundings is impossible. However, no statement is made about to what extent the aluminum-nitride layer is impermeable for aluminum ions or bodily fluids.
Consequently, there is a need to provide an operation tool or surgical instrument that is suitable for MR-guided or MR-based operations and examinations, however, one that can be produced more easily and economically and can effectively prevent a peeling off of the aluminum in the body.
The present invention is based on the object of providing a surgical instrument that is suitable for MR-guided or MR-based operations and/or examinations, in particular on human or animal bodies, wherin the surgical instruments can be produced more easily and more economically with very good mechanical characteristics.
A fundamental idea of the invention is to use aluminum or an aluminum compound preferably consisting primarily of aluminum or an aluminum alloy or a mixture thereof as base material or main part of the surgical instrument or at least for its working section and providing a barrier layer of an inorganic oxide.
In the present invention, the term xe2x80x9csurgical instrumentxe2x80x9d should be understood primarily as device or instrument that can be used in particular in an operation or examination, in particular on human or animal bodies, namely, preferably, inserted and/or, for example, is used to have an effect on bodily tissue. In a broader sense, however, general surgical instruments and other instruments, devices and aides that are used for operations and/or examinations and, in particular, come into contact with the respective body should also be understood under this term.
In the present invention, xe2x80x9cworking sectionxe2x80x9d should be understood as at least a part of the surgical instrument that is essential for the defined function of the surgical instrument and/or primarily comes into contact with or is inserted in the body being operated and/or examined. In this case, it is particularly a matter of a relatively small part in the area of the respective operation or examination location. The surgical instrument can, for example, have further sections or parts, such as a handle or the like, that also comes into contact with the body or is inserted therein.
Tests have shown that aluminum is at least partially invisible in a magnetic resonance tomograph (image). Thus, with the use of MR, the artifacts that are otherwise generally present in the case of metals do not emerge.
In view of MR-compatibility, it can suffice to have only one working section, for example a canula, a scalpel, a hook, a clamp, a bracket or the like located immediately at the respective operation location, which consists at least essentially of the proposed base material. However, the entire surgical instrument is preferably manufactured at least essentially of the proposed base material.
However, as an alternative, the base material can also form only a coating or layering on another carrier material, wherein the surgical instrument or its active area can consist essentially of the carrier material, i.e. of another material.
Furthermore, the base material, in particular the entire surgical instrument, is covered by a barrier layerxe2x80x94at least on open surface areas or surface areas accessible to bodily fluids/tissues. The barrier layer is impermeable for aluminum, aluminum ions and bodily fluids. This prevents aluminum ions, which are thought to be harmful, from dissolving in the body.
The amorphous barrier layer of an inorganic oxide is very simple and can correspondingly be economically produced, e.g. by oxidizing the aluminum of the base material.
Furthermore, a very high quality impermeability can be achieved even at a low thickness with an inorganic oxide, in particular silicon dioxide or aluminum oxide, so that the barrier layer can be formed more thinly. This allows, depending on the method, a low layering time, i.e. a fast and therewith economical formation of the barrier layer.
Ripping or flaking of the barrier layer can be countered by the possible thin formation.
A preferred embodiment provides that the working section or the surgical instrument having an MR-visible material is marked. In this case xe2x80x9cto markxe2x80x9d means that the material is provided, at points or spread out, in a sufficient amount in order to make the working section or the entire surgical instrument visible without creating the undesired artifacts (defect image or covering of other areas) of MR.
The MR-visible material, such as a precious metal, heavy metal or iron can be immediately added to the base material in a suitable amount, wherein the aluminum can, for example, be xe2x80x9cmade impurexe2x80x9d for marking with an adequate amount. An aluminum alloy cannot be taken into consideration in this case, since the amount of material to which aluminum is to be added is too low.
However, the MR-visible material for marking is preferably not directly integrated in to the base material, but rather provided in or on the barrier layer. For example, the MR-visible material can be contained in the barrier layer material and/or can be incorporated in the hollow spaces formed in the barrier layer.